1. Field of the Invention
The present invention relates to a centrifugal casting appratus for dentistry, which is useful in the production of metal products for dentistry such as gold crowns and dental plates.
2. Description of the Prior Art
Conventionally available among apparatus for casting metal products for dentistry such as gold crowns and dental plates has been a centrifugal casting apparatus which serves to cast molten metal from a crucible into a mold on a turntable rotating in the horizontal plane.
In such a centrifugal casting apparatus, metal is molten by a melting means such as an arc-heating one, and a crucible with the molten metal is allowed to rotate together with a mold thereby cast the molten metal from the crucible into the mold by centrifugal force, whereby two major problems have been encountered; one is the oxidation of the molten metal surface attributed to its contacting with oxygen in the air during a prolonged period of time required for casting, and the other involving solidification without allowing molten metal to fill sufficiently into the extremities of mold cavities because of a lack of centrifugal force in the initial stage of casting. In other words, these problems are attributed to the fact that after metal is completely molten, it requires several seconds since initiation of rotation to produce a high rate of rotation enough to obtain centrifugal force of the magnitude for casting. This has led to the finding that these problems may be able to be solved if great centrifugal force which enables casting can be imparted immediately upon melting of metal for dentistry.
The centrifugal casting apparatus conventionally utilized have a crucible, a mold, etc. disposed on a turntable revolving in the horizontal plane and have to be allowed the level area of a determined size necessary to insure the rotation thereof, resulting in a increased dimension of frames of the apparatus and bringing about difficulties in observing or inspecting a state of metal melting in the crucible from the outside. And, it is strongly desired to improve and eliminate these problems.